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Binary compounds of hydrogen are binary chemical compounds containing just hydrogen and one other chemical element. By convention all binary hydrogen compounds are called hydrides even when the hydrogen atom in it is not an anion.〔''Concise Inorganic Chemistry'' J.D. Lee〕〔''Main Group Chemistry'', 2nd Edition A.G. Massey〕〔''Advanced Inorganic Chemistry'' F. Albert Cotton, Geoffrey Wilkinson〕〔''Inorganic chemistry'', Catherine E. Housecroft,A. G. Sharpe〕 The hydrides can be grouped into several clusters. Binary hydrogen compounds in group 1 and group 2 are the ionic hydrides (also saline hydrides) with the exception of beryllium hydride which has intermediate properties between ionic and covalent. Beryllium hydride is electron-deficient and polymeric with bridging hydrogen atoms. Group 1 and 2 hydrides are high melting solids that react violently with water. Elements in group 3, group 4, chromium in group 5, the Lanthanoids and the Actinoids form metallic hydrides, characterised by their metallic luster and hardness, their ability to conduct electricity and their magnetic properties. They are also less dense that the metal itself. Metallic hydrides form by absorption of hydrogen by the respective metal, sometimes requiring elevated pressures, and other times occurring spontaneously. They can be thought of as a solid solution with atomic hydrogen as an interstitial element or as an interstitial hydride. Many metallic hydrides are non-stoichiometric. Examples are TiH1.7, NbHx (0 > x < 1), LaH2.87 and YbH2.55. Exceptions are stoichiometric compounds of uranium (trivalent) UH3, europium (divalent) EuH2 and americium AmH2. The affinity for hydrogen for the other d-block elements is low. Therefore elements in this block do not form hydrides (the hydride gap) under standard temperature and pressure with the notable exception of palladium.〔''Inorganic Chemistry'' Gary Wulfsberg 2000〕 Palladium can absorb up to 900 times its own volume of hydrogen and is therefore actively researched in the field hydrogen storage. In other oxidation states d-block elements again form a wide range of transition metal hydrides for example the rhenium ion in potassium nonahydridorhenate. Elements in group 13 to 17 (p-block) form covalent hydrides (or nonmetal hydrides). In group 12 zinc hydride is a common chemical reagent but cadmium hydride and mercury hydride are very unstable and esoteric. In group 13 boron hydrides exist as a highly reactive monomer BH3, as an adduct for example ammonia borane or as dimeric diborane and as a whole group of BH cluster compounds. Alane (AlH3) is a polymer. Gallium exists as the dimer digallane. Indium hydride is only stable below . In group 14 the total number of possible binary saturated compounds with carbon of the type CnH2n+2 is very large. Going down the group the number of binary silicon compounds (silanes) is small (straight or branched but rarely cyclic) for example disilane and trisilane. For germanium only 5 linear chain binary compounds are known as gases or volatile liquids. Examples are n-pentagermane, isopentagermane and neopentagermane. Of tin only the distannane is known. Plumbane is an unstable gas. Non-classical hydrides are those in which extra hydrogen molecules are coordinated as a ligand on the central atoms. These are very unstable but some have been shown to exist. == The periodic table of the stable binary hydrides == The relative stability of binary hydrogen compounds and alloys at standard temperature and pressure can be inferred from their standard enthalpy of formation values.〔Data in KJ/mole gas-phase source: ''Modern Inorganic Chemistry'' W.L. Jolly〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「binary compounds of hydrogen」の詳細全文を読む スポンサード リンク
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